Devices exist which provide bidirectional data over power mains (e.g. building infrastructure AC power wall outlets and wiring providing the power to them) such as described in copending application Ser. No. 10/871,361, incorporated by reference. The apparatus describe therein, as well as other devices, are operable only so long as the path of the power mains has sufficient fidelity in the range of signals that the apparatus or devices apply and receive their data signals, such as within the range of 1-50 MHz. various data-over power line standards and protocol, i.e. HomePlug, Universal Powerline Association (UPA). However, in many building applications, the path between power mains and data equipment passes through an Uninterruptible Power Supply (UPS) which intentionally, such as with internal filtering, or accidentally degrades the data signal path to make power mains devices which are intended to pass data over the power main, e.g. power mains data transceivers, inoperable.